Use the ZoomWidth property to change how large the chart will appear on horizontal axis, if the ZoomWidthMode property is exCustomSize. Use the ZoomHeight property to specify how large the chart will appear on vertical axis. Use the MinZoomWidth/MaxZoomWidth property to specify the limits on horizontal axis when the user performs resizing/zooming/shrinking. 

The following VB sample enlarges the chart to 200%:

With ChartView1
        .BeginUpdate
            .ZoomWidthMode = exCustomSize
            .ZoomWidth = 2
            .ZoomHeightMode = exCustomSize
            .ZoomHeight = 2
        .EndUpdate
End With

The following C++ sample enlarges the chart to 200%:

m_chartview.BeginUpdate();
m_chartview.SetZoomWidthMode( 1 /*exCustomSize*/ );
m_chartview.SetZoomWidth( 2 );
m_chartview.SetZoomHeightMode( 1 /*exCustomSize*/ );
m_chartview.SetZoomHeight( 2 );
m_chartview.EndUpdate();

The following VB.NET sample enlarges the chart to 200%:

With AxChartView1
    .BeginUpdate()
    .ZoomWidthMode = EXORGCHARTLib.ZoomModeEnum.exCustomSize
    .ZoomWidth = 2
    .ZoomHeightMode = EXORGCHARTLib.ZoomModeEnum.exCustomSize
    .ZoomHeight = 2
    .EndUpdate()
End With

The following C# sample enlarges the chart to 200%:

axChartView1.BeginUpdate();
axChartView1.ZoomWidthMode = EXORGCHARTLib.ZoomModeEnum.exCustomSize;
axChartView1.ZoomWidth = 2;
axChartView1.ZoomHeightMode = EXORGCHARTLib.ZoomModeEnum.exCustomSize;
axChartView1.ZoomHeight = 2;
axChartView1.EndUpdate();

The following VFP sample enlarges the chart to 200%:

With thisform.ChartView1
    .BeginUpdate
    .ZoomWidthMode = 1 && exCustomSize
    .ZoomWidth = 2
    .ZoomHeightMode = 1 && exCustomSize
    .ZoomHeight = 2
    .EndUpdate
EndWith